Physics Exercises/Blackbody radiation

What is the maximum efficiency of the black body as a source of visible light? Assume "visible light" means EM radiation between 380 nm and 750 nm.

(Hint: First work out the optimal surface temperature (it should be close to the surface temperature of the sun), and then work out the efficiency. Integral using Planck's blackbody radiation formula required.)

What is the maximum temperature of the light side of the moon? Assume that the amount of sunlight incident on the moon is also given by the solar constant.